Drone motor performance - Revision history

Jca: /* Trust constant */

2020-11-28T16:23:54Z

Trust constant

← Older revision		Revision as of 18:23, 28 November 2020
Line 77:		Line 77:
	Trust-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional to rotation speed (in radians per second) to the power of 2.		Trust-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional to rotation speed (in radians per second) to the power of 2.

	Kt ~ 0.~~027~~ for the 13" propeller and		Kt ~ 2.7e-5 for the 13" propeller and

	Kt ~ 0.~~037~~ for the 14" propeller		Kt ~ 3.7e-5 for the 14" propeller

Jca: /* Drag constant */

2020-11-26T13:52:01Z

Drag constant

← Older revision		Revision as of 15:52, 26 November 2020
Line 63:		Line 63:
	[[File:3508-700-drag-constant.png \| 600px]]		[[File:3508-700-drag-constant.png \| 600px]]

	Drag-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional ~~with~~ rotation speed (in radians per second) to the power of 3.		Drag-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional to rotation speed (in radians per second) to the power of 3.

	Kd ~ 1.5e-9 for 13" propeller and		Kd ~ 1.5e-9 for 13" propeller and

Jca: /* Trust constant */

2020-11-26T13:51:47Z

Trust constant

← Older revision		Revision as of 15:51, 26 November 2020
Line 75:		Line 75:
	[[File:3508-700-trust-constant.png \| 600px]]		[[File:3508-700-trust-constant.png \| 600px]]

	Trust-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional ~~with~~ rotation speed (in radians per second) to the power of 2.		Trust-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional to rotation speed (in radians per second) to the power of 2.

	Kt ~ 0.027 for the 13" propeller and		Kt ~ 0.027 for the 13" propeller and

	Kt ~ 0.037 for the 14" propeller		Kt ~ 0.037 for the 14" propeller

Jca: /* Trust constant */

2020-11-26T13:51:20Z

Trust constant

← Older revision		Revision as of 15:51, 26 November 2020
Line 77:		Line 77:
	Trust-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 2.		Trust-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 2.

	Kt ~ 0.~~037~~ for the 13" propeller and		Kt ~ 0.027 for the 13" propeller and

	Kt ~ 0.~~027~~ for the 14" propeller		Kt ~ 0.037 for the 14" propeller

Jca: /* Trust constant */

2020-11-26T13:43:11Z

Trust constant

← Older revision		Revision as of 15:43, 26 November 2020
Line 77:		Line 77:
	Trust-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 2.		Trust-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 2.

	Kt = 0.037 for the 13" propeller and		Kt ~ 0.037 for the 13" propeller and

	Kt = 0.027 for the 14" propeller		Kt ~ 0.027 for the 14" propeller

Jca: /* Drag constant */

2020-11-26T13:42:56Z

Drag constant

← Older revision		Revision as of 15:42, 26 November 2020
Line 64:		Line 64:

	Drag-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 3.		Drag-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 3.
	~~Approximately~~ Kd = 1.5e-9 for 13" propeller and Kd = 2e-9 for the 14" propeller.
			Kd ~ 1.5e-9 for 13" propeller and

			Kd ~ 2e-9 for the 14" propeller.

	=== Trust constant ===		=== Trust constant ===

Jca: /* Trust constant */

2020-11-26T13:42:21Z

Trust constant

← Older revision		Revision as of 15:42, 26 November 2020
Line 73:		Line 73:

	Trust-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 2.		Trust-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 2.

			Kt = 0.037 for the 13" propeller and

			Kt = 0.027 for the 14" propeller

Jca: /* Drag constant */

2020-11-26T13:40:47Z

Drag constant

← Older revision		Revision as of 15:40, 26 November 2020
Line 64:		Line 64:

	Drag-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 3.		Drag-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 3.
			Approximately Kd = 1.5e-9 for 13" propeller and Kd = 2e-9 for the 14" propeller.

	=== Trust constant ===		=== Trust constant ===

Jca at 13:36, 26 November 2020

2020-11-26T13:36:41Z

← Older revision		Revision as of 15:36, 26 November 2020
Line 50:		Line 50:
	(Right) Static transfer gain as a function of ESC pulse width.		(Right) Static transfer gain as a function of ESC pulse width.
	The transfer gain is fairly constant (within a factor 2) in the useful trust area.		The transfer gain is fairly constant (within a factor 2) in the useful trust area.

			=== Drag constant ===

			Drag constant is calculated based on the change in motor current divided with the change in rotation speed squared

			Kd = dI*Km / d(w²)

			At different motor controller pulse length (all recorded with a battery voltage of 11 V).

			This value is intended to be used when simulating a drone motor

			[[File:3508-700-drag-constant.png \| 600px]]

			Drag-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 3.

			=== Trust constant ===

			The trust constant gives the relation to trust (in Newton) from the rotation speed (in radians per second) squared.

			[[File:3508-700-trust-constant.png \| 600px]]

			Trust-constant for the 3508-700 motor with 13" and 14" propeller, the drag is proportional with rotation speed (in radians per second) to the power of 2.

Jca: Created page with "Back to Drone control ==Motor and propeller performance== Measured with the "motortest" firmware and the python app below. The used motor is the 3508-700KV Turnigy Mult..."

2020-10-10T07:10:06Z

Created page with "Back to Drone control ==Motor and propeller performance== Measured with the "motortest" firmware and the python app below. The used motor is the 3508-700KV Turnigy Mult..."

New page

Back to [[Drone control]]

==Motor and propeller performance==

Measured with the "motortest" firmware and the python app below.
The used motor is the 3508-700KV Turnigy Multistar 14 Pole Brushless and a 14x5.5 carbon propeller.
The ESC is a Hobby-wing x-rotor 40A controller.

=== Time responce ===

[[File:3508-700-14x5.5-11v.png | 600px]]
[[File:3508-700-14x5.5-15v.png | 600px]]

With 11 V supply (left) and 15V (right).
From 1.1ms to the ESC (idle) to 1.9ms almost full throttle. The ESC update frequency is 400 Hz.

=== Static response 3508-700 ===

Transfer measurement with different propellers.
The Hobby Wing controller is calibrated to 1ms=off, 2ms=full power.
Measurement is in a fixed setup on a scale with 1g resolution. Propeller 50cm above ground level.
Power is a lab power supply. Motor and ESC temperature below 50 degree C.

The propellers
* 8"x 3.8 APC composite propeller
* 9"x 4.5 APC composite propeller
* 13"x 4.5 carbon fiber
* 14"x 5.5 carbon fiber
* 18"x 5.5 carbon fiber Quanum

[[File:trust-per-power-3508-700.png | 600px]]
[[File:rpm-per-power-3508-700.png | 600px]]

(Left) trust delivered for each propeller size as a function of motor input power.
It shows that bigger propellers are more power-efficient.
(Right) RPM as a function of input power.

=== Static gain 3508-700 ===

For the same data as above, bot now related to the ESC input pulse width.
The ESC has been calibrated to 1ms is zero power, 2ms is maximum power.
All data has been scaler to 11V, as the curves scale almost 1:1 with the input voltage.

[[File:trust-TF-3508-700.png | 600px]]
[[File:transfer_gain_N-per-ms.png | 600px]]

(Left) Trust curve as a function of ESC pulse width. Bigger propellers require more power but deliver more trust.
(Right) Static transfer gain as a function of ESC pulse width.
The transfer gain is fairly constant (within a factor 2) in the useful trust area.